Paper sizing composition



United States Patent N0 Drawing. Filed Nov. 6, 1959, Ser. No. 851,242 8 Claims. (Cl. 106-243) This invention relates to paper sizing compositions; and, more particularly, to paper sizing compositions composed of major amounts of hydrogenated animal fats or mixtures thereof with minor amounts of hydrogenated vegetable fats in combination with minor amounts of alkali treated or neutral, partially saponified animal, vegetable or marine animal fats or oils, which are useful in aqueous dispersions in the beater engine sizing of paper pulp.

It has been customary to size writing, printing and Wrapping papers for many years in order to control the absorption and consequent spreading of inks subsequently 7 3,066,039 Patented Nov. 27, 1962 ice throughout the fibers; and as well, uniformly over the surface of each of the individual particles of fiber.. Still another object of this invention is to provide a paper sizing which forms a coating on the fibers that is sub stantially free of microscopic bubbles and which strongly adheres to both the paper fiber and to any fillers added to the pulp suspensions, thus enhancing the opacity and brightness of the paper. A still further object of this invention is to provide a paper sizing composition which affords a paper of high porosity which, however, possesses a resistance to water and humidity that is greater than applied to the surface ofthe paper sheet. The uses of casein and aqueous dispersions of rosin for this purpose were developed very early in the history of the papermaking art and rosin-sizes are still the-most important in commercial use today. Numerous attempts have been made to improve rosin sizes, including the modification of the rosin or the replacement of all, or part, of the rosin with various substances; such as, for example, synthetic rosins, gums, waxes, bituminous and asphaltic materials. In spite of these efforts to improve rosin sizes, aqueous dispersions of partially saponified rosin have remained the preferred sizing material of the paper industry. These aqueous dispersions are ordinarily added to the suspensions of pulp in the beater engine in amounts sufficient to provide from about one-half to about five percent by weight of rosin based on the dry weight of the pulp. The alkali neutralized rosin is precipitated as, theoretically, free rosin on the surfaces of the pulp fibers.

The above-described standard rosin paper sizes are known to possess certain disadvantages. One of the greatest disadvantages of rosin sizes is that they produce foaming at numerous stages in the paper-making process; including such stages as, for example, the beater engine, the head box or pressure-forming chamber for depositing the pulp suspensions on the moving screen, and in the white-water recirculating system. Aqueous dispersions down of the machines with great frequency to replace the blanket. The efliciency of rosin paper sizes is also not as great as is desired. Thus, rosin sizes do not deposit uniformly, throughout the fibers of the paper nor over the surface of the individual particles of fiber and the adhesion of the rosin size to the fibers of the paper is not good. It has also been determined'that the rosin size coating on the fibers contains a high percentage of bubbles which are microscopic in size, but which are detrimental to the appearance and uniformity of the quality of the paper. Rosin sizes also have little effect on the opacity and brightness of the paper.

It is the principal object of this invention to provide a paper sizing composition which, when added as an aqueous dispersion to a suspension of paper pulp, does not foam at any stage in a paper-making machine which does not impair the liquid absorbing properties of blankets or like elements of paper-making machines. Another object of this invention is to provide a paper sizing composition which, when added as an aqueous dispersion in the beater, is substantially uniformly distributed that imparted to paper by the same amount of rosin size. It is also an object of this invention to provide a paper sizing composition which eliminates free dust which forms when a paper sized therewith is chopped or otherwise comminuted for any purpose, including for reuse in paper making. In addition, a paper sized with the compositions of this invention need not be resized when such apaper is reused in a paper-making process.

The disadvantages of the standard rosin paper sizing compositions in use today are overcome and the aboveenumerated objects are accomplished by this invention which, briefly, consists of preparing a paper sizing composition composed of a major amount of a hydrogenated animal fat having titer in the range of from 45 to about 61 C. or a mixture of a major amount of such a hydrogenated animal fat and a minor amount of hydrogenated vegetable fat or oil having a titer in the range of from 45 to 70 C.; and, preferably, about 65 C.; and, in combination therewith, a minor amount of an alkali treated animal, vegetable, or marine animal fat or oil having a melting point above about 30 C. The paper sizing compositions comprising this invention are prepared by adding the natural, unsaponified animal, vegetable or marine animal fat or oil to the hydrogenated fat or oil in the ratio of from about 2 to about 5 parts by weight of natural fat or oil to about 10 parts by weight of hydrogenated fat or oil. About from 0.50 to about 1.50 parts by weight of an alkali saponifying agent is added, preferably as an aqueous solution, to the mixture of hydrogenated fat or fats and the natural or unsaponified fats or oils, and the mixture is then heated to complete reaction. The reaction which is thus carried out results in the formation of the corresponding alkali metal salt of any free fatty acids in the natural or unsaponified fat or oil and the saponification of a portion of the natural or unsaponified fats or oils. The heating is then continued depending upon the amount of water added to the reaction mixture at the outset, until the moisture content of the mass is reduced to about 30 percent by Weight, or less, and the mass is then cooled until it is solid. The product thus obtained can be powdered and may be used in sizing paper by adding it to any desired amount of heated water with agitation, to form an aqueous dispersion of a paper sizing composition. The paper sizing composition in the form of an aqueous dispersion may then be added to the suspension of pulp in the beater in an amount sufficient to provide from about 0.5 to about 4 percent of dry size based on the dry weight of the paper pulp.

The hydrogenated fats or oils employed in the paper sizing compositions comprising this invention consist of hydrogenated animal fats or oils having titer in the range of from 45 to 61, but it is preferred such hydrogenated fats and oils having a titer in the range of from about 55 to 61 C.; and, specifically, a titer of about 57. The hardened or hydrogenated fats are prepared by the customary commercial method for hydrogenating such fats 'or oils which consists of hydrogenating in the presence of a reduced nickel catalyst on a kieselguhr or Filtercel carrier at a temperature in the range of-from- -190 C.

and at a pressure in the range of from -40 pounds per square inch. The hydrogenation is continued until test portions show the fat or oil has acquired a titer of at least about 55 C. The hydrogenation forms saturated acids, in part, and also converts linoleic acid into trans and isomeric forms of oleic acid (isooleic) having highe melting points than normal fatty acids. The oil may be filter pressed while hot to remove the catalyst and carrier, and is then cooled. If desired it may be stripped with steam to remove any residual odors and liquid fractions still present. The known methods of hydrogenating fats are described by O. H. Wurster, Ind. Eng. Chem. 3 2, 1193 (1940) and form no part of this invention. The preferred hydrogenated animal fats for use in this invention are the tallows, or depot fats of herbivorous animals, sheep and cattle. Thus, it is preferred to hydrogenate beef tallow to a titer of about 57 to 61, or mutton tallow having a titer in the range of 33.5 -49 C. until these fats show a titer of about 57 C.-58.5 C. The titer number of the beef tallow that is hydrogenated is 40-46 and that of the mutton tallow used 40-48.5. Lard having an average melting point of about 45 C. and a titer number of about 42 may be hydrogenated until it has a titer in the range of 57 60 C. to produce what is known as lard flakes which may be used in this invention. The chemical composition of the foregoing fats is given in The Chemical Constitution of Natural Fats, by T. P. Hilditch, published by Wiley, New York, 1940. Other hydrogenated animal fats, including beef marrow fat, bone fat, chicken fat, goose fat and horse fat may be used, but these have little commercial importance and the use thereof is not preferred since the best sizing compositions according to this invention are prepared from the above very hard beef tallows.

The paper sizes of this invention may also be prepared by replacing a minor portion of the hard hydrogenated animal fats; such as, for example, beef tallow, having a titer in excess of 55 C., with very hard hydrogenated vegetable fats or oils. Thus, up to 40 percent by weight of the total amount of hydrogenated fat employed may be a hydrogenated vegetable fat or oil having a titer in excess of about 55 C.; and, preferably, of about 65 C. It is preferred to employ either a hydrogenated soyabean oil having a titer of about 65 C., or in the range of 64.5 to 66.5 C., or hydrogenated olive oil having a titer of at least about 65 C. Other hydrogenated vegetable fats or oils may be used; such as, for example, hydrogenated cottonseed oil titer 60 C., and hydrogenated castor oil titer 87 C. Other hydrogenated vegetable oils which may be used include hydrogenated palm oil, peanut oil, or sesame oil. The amount of hydrogenated vegetable fat or oil used with hydrogenated animal fat is preferably in the range of from about one to four parts by weight of hydrogenated vegetable fat or oil to from 9 to 6 parts by weight of hydrogenated animal fat. It is preferred to use about 3 parts by weight of the hydrogenated vegetable fat or oil to about 7 parts by weight of the hydrogenated animal fat.

The hydrogenated animal fats or mixtures thereof with hydrogenated vegetable fats or oils which have been described above are combined in admixture with a minor amount of an alkali treated partially saponified animal marine animal or vegetable fat or oil having a melting point above about C., and from which the free glycerin has been removed. Such fats and oils are known commercially as acid fats. For the purposes of this invention it is preferred to use an alkali treated, partially saponified tallow acid fat derived from beef tallow having a titer above 30 C.; and, preferably in the range of 43 to 46 C. Other fats and oils which may be saponified partially and used in this invention include animal fats; such as, for example mutton tallow and lard, marine animal fats, in-cluding menhaden, cod liver, herring or sardine; and vegetable fats or oils, such as, for example, olive oil, cottonseed oil, peanut oil or castor oil.

The paper sizes comprising the invention herein are produced by mixing the hydrogenated animal fat with a minor amount of a natural animal fat, marine animal fat or vegetable fat having a titer above 30 C. and an aqueous solution of an alkali saponification agent. If a minor portion of the hydrogenated animal fat is replaced with hydrogenated vegetable fat oil oil, the latter is added to the mixture at the same time the hydrogenated animal fat is added. The above mixture may be prepared in a steamjacketed open kettle. The amounts of the several components of the mixture used are important. Thus, about 10 (ten) parts by weight of the hydrogenated animal fat or not more than four (4) parts by weight of hydrogenated vegetable fat and not less than six (6) parts by weight of hydrogenated animal fat are mixed with from about two (2) to not more than five (5) parts by weight of the natural acid fats or oil. It is preferred to use between about three (3) to about four (4) parts by weight of the acid fat with ten (10) parts by weight of the total amount of hydrogenated fat used. To the above mixture of fats is then added ten (10) parts by weight of an aqueous solution of an alkaline saponification agent; such as, for example, calcium, magnesium, sodium or potassium hydroxide or carbonate. It is preferred to employ caustic for this purpose. It is preferred to use a solution containing about one 1%) percent by weight of the saponifying agent, but concentrations in the range of from about 0.50 to about 1.5 percent by weight may be used. The mixture thus prepared is boiled at C. for from one-quarter to one-half hour to complete the saponification reaction, It is preferred that the reaction mixture be agitated during the heating to provide a homogeneous mixture of the unreacted materials and the reaction products obtained. The heating and agitation may be continued to evaporate the excess moisture or until the moisture content of the mixture is reduced to about 30 percent by weight. This time will vary depending upon the amount of water used in the original mixture. The mixture thus obtained is then allowed to cool and solidify. It may then be ground to powder of fine particle size and placed in containers.

The above procedure may be carried out in an autoclave provided with a stirring mechanism at the autogenous temperature of from 2-4 atmospheres for about 10 minutes and then the mixture may be dried and cooled as above described. When the reaction is carried out in an autoclave it is not essential to use aqueous solutions of caustic or other saponifying agent; and, if desired, a solid alkali may be added to the mixture of fats in the autoclave. Alternatively, the above described mixture may be prepared and heated until the neutralization and saponification reactions are completed; and thereafter the hot liquid mass may be spray dried in conventional equipment to produce small, dry granules which may be packaged when cool.

The paper sizing compositions comprising this invention are dispersed in water and the aqueous dispersions used in the paper-making process in the same manner that aqueous dispersions of partially saponified rosin are used for sizing purposes. A paper sizing composition, prepared as described above, is added to heated water with agitation and in the proportion of about 20 parts by weight of sizing composition to parts by weight of boiling water. The aqueous dispersion thus prepared is cooled and is then added to the beater containing the the suspension of paper pulp and filler. The aqueous dispersion is used in an amount sufiicient to provide between about 4 and 6 percent; and preferably, about 5 percent by weight of sizing composition based on the dry weight of the paper pulp. Papermakers alum must be added to the suspension of sizing and pulp in the amount of from about 3 to 4 percent based on the weight of the pulp to provide a pH of between about 4.5 and 5.5; and preferably about 5.

The sizing compositions of this invention may be used to size any type of pulp which is customarily sized with alkaline rosin sizes. The suspensions of paper pulp to which the aqueous dispersion of the sizing compositions of this invention are added may also contain the usual paper fillers; such as, for example, titanium dioxide and pigmentary silica fiocs in amounts of about 8 to percent by Weight based on the weight of the dry pulp.

Sized pulp is dried preferably at a minimum temperature of 100 C. which is a condition attained on standard paper drying rolls. The best mode of carrying out this invention is set forth in the following examples:

Example 1 Ten (10) parts by weight of hydrogenated beef tallow having a titer of 57 C. were placed in a steam jacketed open kettle and three (3) parts by weight of natural beef tallow having a titer of 40 C. from which the free glycerin was removed were added to the hydrogenated tallow. Ten (10) parts of aqueous caustic soda 10 B. (0.75% by weight) were added to the kettle. The mixture was boiled at 100 C. for minutes and was agitated with a rotary stirring mechanism during the heating. The heating and stirring were continued for minutes to reduce the moisture content of the reaction mixture to 30% by weight and the reaction mixture was then allowed to cool and solidify. The solid mass was broken up in the kettle, removed therefrom and ground into a powder in a harnmer mill.

20 (twenty) parts by weight of the above composition was added to one hundred twenty (120) parts by weight of boiling water with agitation to form a homogeneous aqueous dispersion. The aqueous dispersion was added to a laboratory beater containing a suspension of 100 percent linen rag pulp and 8% ,by weight titanium dioxide based on the weight of the pulp, in amount sufiicient to provide 5% by weight of sizing based on the weight of the dry pulp. About 4% by weight of papermakers alum, based on the Weight of the dry pulp, was added to the beater. The sized suspension of pulp was used to prepare hand sheets on a standard TAPPI hand sheet-forming test machine and hand sheets having an excellent crisp feel were obtained.

Example 2 A paper sizing composition was prepared as described in Example 1, above, with the sole exception that 6 parts by weight of a hydrogenated beef tallow having a titer of 58 C. and 4 parts by weight of a hydrogenated soyabean oil having a titer of 64.5 C. were mixed with the natural, unsaponified beef tallow and aqueous caustic as described in Example 1. The paper sizing composition obtained with these starting materials was added in an aqueous dispersion to a suspension of titanium dioxide filler and 100 percent cotton rag pulp. Hand sheets were prepared after the addition of alum to the suspension which were of excellent quality.

Example 3 A paper sizing composition was prepared as described in Example 2 with the sole exception that 2 parts by weight of a hydrogenated olive oil having a titer of 645 were used in lieu of the hydrogenated soyabean oil with 8 parts by weight of a hydrogenated beef tallow having a titer of 585 C. Hand sheets of high quality were produced from the suspensions of pulp sized with the composition thus obtained.

Example 4 Ten (10) parts by weight of hydrogenated mutton tallow having a titer of 60 C. was mixed with four (4) parts by weight of olive oil and ten 10) parts by weight of a 1.2% aqueous solution of caustic soda in an autoclave having a rotary stirrer. The mixture was heated at 3 atmospheres for ten (10) minutes, the pressure in the autoclave was gradually removed and heating and stir- 6 a ring continued for minutes to dry the mass. The product was cooled, solidified, comminuted into a dry powder. It was then made into an aqueous dispersion as described in Example 1 and used to size a suspension of filler and linen rag pulp as described in Example 1. Excellent hand sheets were prepared from such suspensions.

Example 5 The method of Example 4 was followed except that 2 parts by weight of menhaden oil were used in lieu of 4 parts by weight olive oil. The sizing composition thus obtained was used to size a linen rag pulp as described in Example 1 to produce hand sheets of fine quality.

In carrying out the processes described in each of the above examples it was observed that the foaming occurred in the laboratory beater after the addition of the aqueous dispersion of the sizing composition thereto. The same result was observed when suspensions of pulp sized with compositions of this invention were in a head box from which the stock was fed to the endless wire of a Fourdrinier machine and no undue foaming was detected in the white water recycling system used therewith. It has also been observed that the endless blankets to which the paper web is transferred from the moving wire screen may be used for from 4 to 5 weeks without having to be removed for cleaning. When aqueous dispersions of partially saponifiedrosin size are used the blankets cease to absorb water from the transferred web efficiently in about 2 Weeks and must be removed from the machine and washed to remove the deposited sizing therein.

The hand sheets produced by the above examples were highly porous and were found to be as resistant to water and humidity as those obtained using standard rosin sizing in an amount, based on the weight of the dry pulp, equal to the amount of sizing used in the above examples. The sizing in the hand sheets was found to be substantially uniformly distributed throughout the body of the sheet and a microscopic examination established that the individual fibers were practically uniformly sized. The size coating on the fibers was almost free of bubbles. The opacity and brightness measurements of the hand sheets produced by the above examples, by standard TAPPI methods, indicated greater opacity and brightness than is obtainable in hand sheets produced with the same amount of filler in the pulp suspension and an amount of standard rosin size equal to that used in the above examples. This is believed to de due to the gerater adhesion of the sizing compositions of this invention to both the pulp fiber and the filler than that of standard rosin sizes, as well as to the uniformity of distribution of the size over the fibers.

The mechanism by which the paper sizings comprising this invention accomplishes the advantages discussed hereinabove is not understood. It is wholly unexpected to obtain a sizing effect from fats or oils, in general, since the use of such materials in the paper industry has been principally restricted to greaseproofing and waterproofing papers. In the present invention, however, it has been found that the paper sizings hereinabove described have little or no grease or waterproofing effect on paper in the common and accepted meaning of these terms in the paper art. The homogeneous mixture of hydrogenated animal fats having titers preferably of at least above 55 C. or of mixtures thereof with a minor amount of a hydrogenated vegetable fat having a titer of at least about 60 C. and a minor amount of glycerin-free, neutralized and partially saponified natural animal, marine animal or vegetable fats or oils having titers above 30 C. cooperate uniquely. The neutralization and partial saponification of the glycerin free, natural fats or oils in the presence of the hydrogenated fats or mixtures thereof, above, provide especially good results when the sizings so prepared are used in aqueous dispersions in the beater. These advantages, moreover, are not attained when a hydrogenated marine animal fat or oil is used in place of the hydrogenated animal fat or hydrogenated vegetable fats or oils.

Thus, it has been found that sizing compositions prepared with hydrogenated marine animal fats or oils result in the production of hand sheets having a somewhat oily feel and which are limp and devoid of the crisp feel desired in a writing or bond paper.

This application is a continuation in part of our abandoned applciation Serial Number 823,369, filed June 29, 1959.

We claim:

1. A heater addition paper sizing composition cOnSisting essentially of about ten parts by weight of a hard, hydrogenated fat selected from the group consisting of hydrogenated animal fats having a titer in excess of 55 C. and mixtures consisting of not less than six parts by weight of hydrogenated animal fat having a titer in excess of 55 C. and not more than four parts by weight of hydrogenated vegetable fats having a titer of at least 60 C., in combination with from about two to about five parts by weight of a neutralized, partially saponified, acid fat selected from the group consisting of animal, vegetable and marine animal fats and oils having a titer in excess of 30 C., said neutralized, partially saponified acid fat being a heat reaction product of from about two to five parts by weight of said acid fat and from about 0.50 to about 1.5 parts by weight of an alkali saponifying agent.

2. A beater addition paper sizing composition as set forth in claim 1 wherein said hydrogenated fat consists of hydrogenated animal fat having a titer in the range of from 55 to 61 C.

3. a beater addition paper sizing composition as set forth in claim 1 wherein said hydrogenated fat consists of a mixture of at least six parts by weight of hydrogenated animal fat having a titer in the range of from 55 to 60 C. and up to four parts by weight of hydrogenated vegetable fat having a titer of at least 60 C.

4. A beater addition paper sizing composition as set forth in claim 1 wherein said hydrogenated fat consists of hard, hydrogenated beef tallow having a titer of about 57 C.

5. A beater addition paper sizing composition as set forth in claim 1 wherein said hydrogenated fat is present in a total amount of ten parts by weight and consists of a mixture of at least 6 parts by weight of hydrogenated beef tallow having a titer of about 57 C. and up to 4 parts by weight of hard, hydrogenated soyabean oil having a titer of about 65 C.

6. A beater addition paper sizing composition as set forth in claim 1 wherein said hydrogenated fat is present in a total amount of ten parts by weight and consists of a mixture of at least 6 parts by weight of hydrogenated beef tallow having a titer of about 57 C. and up to 4 parts by weight of hard hydrogenated olive oil having a titer above about 60 C.

7. A beater addition paper sizing composition consisting essentially of 10 parts by weight of hydrogenated beef tallow having a titer of about 585 C. and from 3 to 4 parts of beef tallow having a melting point of about C. and neutralized and partially saponified with about 1 'part by weight of caustic soda.

8. The method of preparing a beater addition paper sizing composition which comprises mixing 10 parts by weight of a hydrogenated fat selected from the group consisting of hydrogenated animal fat having a titer in excess of C. and mixtures thereof wtih up to 4 parts by weight of hydrogenated vegetable fat having a titer of at least C., from 2 to 5 parts by weight of an acid fat having a melting point above 30 C. selected from the group sonsisting of animal, vegetable and marine animal fats and oils; and from about 0.5 to about 1.5 parts by weight of an alkali saponifying agent, heating and agitating said mixture at about C. until said agent has reacted with the components of said acid fat, cooling and solidifying the mixture thus obtained and reducing the cooled mixture to a powder.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,066,039 November 27, 1962 Francisco de Tienda y Ricon et a1,

It is hereby certified that error ap ent requiring correction and that the sai corrected below.

pears in the above numbered patd Letters Patent shouldread as Column 7, line 10, for "heater" r-ead beater line 3O,Ofg(1; "a" read A column 8, line 29 for "0,5 read Signed and sealed this 14th .day of May 1963a (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Commissioner of Patents 

1. A HEATER ADDITION PAPER SIZING COMPOSITION CONSISTING ESSENTIALLY OF ABOUT TEN PARTS BY WEIGHT OF A HARD, HYDROGENATED FAT SELECTED FROM THE GROUP CONSISTING OF HYDROGENTED ANIMAL FATS HAVING A TITER IN EXCESS OF 55* C. AND MIXTURES CONSISTING OF NOT LESS THAN SIX PARTS BY WEIGHT OF HYDROGENATED ANIMAL FAT HAVING A TITER IN EXCESS OF 55*C. AND NOT MORE THAN FOUR PARTS BY WEIGHT OF HYDROGENATED VEGETABLE FATS HAVING A TITER OF AT LEAST 60*C., IN COMBINATION WITH FROM ABOUT TWO TO ABOUT FIVE PARTS BY WEIGHT OF A NEUTRALIZED, PARTIALLY SAPONIFIED, ACID FAT SELECTED FROM THE GROUP CONSISTING OF ANIMAL, VEGETABLE AND MARINE ANIMAL FATS AND OILS HAVING A TITER IN EXCESS OF 30*C., SAID NEUTRALIZED, PARTIALLY SAPONIFIED ACID FAR BEING A HEAT REACTION PRODUCT OF FROM ABOUT TWO TO FIVE PARTS BY WEIGHT OF SAID ACID FAT AND FROM ABOUT 0.50 TO ABOUT 1.5 PARTS BY WEIGHT OF AN ALKALI SAPONIFYING AGENT. 